#include<stdio.h>


int MyStrlen(char* a)
{
    int count = 0;
    
    while(*a != '\0')
    {
        count++;
        a++;
    }
    return count;

}


char *MyStrcpy(char*a,char*b)
{
    while(*b != '\0')
    {
        *a++ = *b++;
        *a = '\0';
    }
    return a;
}


void MyStrcat(char*a,char*b)
{
    MyStrcpy( a + MyStrlen( a ) , b );
}


int main()
{
    char s1[] = "hello";
    char s2[] = "world";
    
    MyStrcat(s1,s2);
    
    printf("此时的s1的值为 %s\n ",s1);
    return 0;
}